The present invention relates generally to high-density electrical interconnections structures and more particularly to such an interconnection structure that may be used in interposer applications and to connect electrical devices to circuit boards.
Microelectronic devices such as state-of-the-art microprocessors require large numbers of reliable connections in increasingly-small areas. As the number of connections between an electronic device and a substrate to which the device is to be mounted increases, the likelihood that just a single connections will not be made or will fail increases.
In “wave soldering,” an electronic components is soldered to a substrate by flowing molten solder over a substrate in which electronic components are mounted. A substrate, to which electronic components are to be soldered, is passed over the flowing, molten solder such that exposed metal and fluxed surfaces on the lower surface of the substrate surface wick the molten solder upward from the solder bath. As the substrate with the wicked, molten solder moves away from the molten solder bath, the solder cools and solidifies, establishing an electrical connection between electronic devices and soldered surfaces of the substrate.
As connection density increases in the electronic arts and lead lengths from electronic devices decreases, the increasing number of connections that must be made make it statistically more likely that even a single connection will not be made or will fail. Even minor irregularities in a substrate's planarity can cause connection problems.
One problem with prior art soldering techniques arises when the contact surfaces of a substrate and an electronic device are separated from each other by different distances. For example, if one or two contact leads or one or two contact surfaces of a microprocessor are more widely separated from a planar substrate than the other contact leads or contact surfaces, the molten solder might not wick between the substrate and the more-distant contact surfaces of the electronic device. Prior art soldering techniques suffer from an inability to make a connection when the spacing or distance between contact surfaces of two devices or surfaces to be joined, varies by more than a small amount.
When even a single connection between an electronic device and its supporting substrate is either not made at the time of manufacture, or fails while in use, the cost to identify a failed electrical connection and to repair it can often exceed the cost to manufacture the product in which the electronic device and supporting substrate operates. Improving the manufacturability of electrical connections and improving the reliability of electrical connections after manufacture would be an improvement over the prior art.
The present invention is directed to a connector structure that is suitable for use in high-density applications, is easy to manufacture and which provides a reliable contact force while avoiding the aforementioned shortcomings.